The determination or estimation of electric load parameters, such as a phase angle (or phase shift) between a voltage supplied to the load and the resultant current flowing through it, the load impedance and its constituent real and imaginary components, for example, is useful to the designer and user of such equipment. In the case of an electrical load comprising an electric motor, common electric motor drive systems typically comprise an electric motor (essentially consisting of a wound coil), a voltage supply source for the motor and a control unit. The voltage supply source often comprises a voltage source inverter for providing an AC supply from an external DC supply. The overall circuit resistance of an electric motor drive system may be considered to consist of the coil resistance, resistance of any interconnecting cables and resistance attributable to the inverter. This latter contribution is due to components such as transistors and shunt resistors. For some applications (for example, high-voltage with low current) the resistance of the cables and inverter are negligible compared with that of the coil. However, for low-voltage applications (for example, 12 or 24 volts supply in automotive vehicle applications) the coil resistance might be so small that the sum of parasite resistances from the inverter and supply cables becomes a significant part of the overall circuit resistance. While the electrical circuit resistance of an electric motor drive system can be affected by the voltage source inverter, variation in inductance is influenced by magnetic field conditions and therefore by the current flowing through the coil. Thus, inductance can vary depending on the operational conditions of the motor. A common approach for determining the resistance and inductance of an electric motor relies on knowledge of the circuit supply voltage and the current flowing. For example, measuring an applied DC voltage and the DC current flowing yields a value for resistance. Measuring an applied AC voltage and AC current flowing yields a value for impedance. Knowing impedance and resistance enables the reactance/inductance to be calculated. However, many electric motor drive systems do not have the capability to measure the real phase voltage applied to the electric motor, which is a limiting factor for precise measurement of the electrical motor parameters. CN 102386835 discloses a method utilising measurements of AC voltage and AC current. US20120194113 describes a method for estimating inductance of a motor. This has the disadvantage that the estimation can only be carried out while the motor is running. U.S. Pat. No. 6,366,865 discloses a method for estimating coil resistance. Hence, known methods require a two-step process in order to estimate resistance and inductance.